One technique for printing an image, especially one defined by video electrical signals, involves the opening of selected subminiature light shutter apertures that are arranged in a row across the path of a sheet containing a photosensitive layer. The apertures are in the form of subminiature circles, squares, or rectangles through which light falls onto pixel areas of comparable size on the sheet. For many photosensitive materials, considerable light is required for their exposure, and either the sheet must move slowly to obtain sufficient exposure of each area, or the light source must be very bright. Techniques for maximizing the utilization of the light source of given intensity, would enable lower intensity light sources and faster exposures of sheets, which would be useful not only for dot matrix type exposure but in other exposure applications.